These are called olive drab cans. The beer companies made the cans this way so they would not reflect on the battle field and help keep our troops safe.

One interesting bit of history is that prior to WW2 no one drank out of a can. They would open the cans and pour the beer in a glass. During the war with the conditions the troops were in a cup or glass was not available so the troops started to drink out of the cans themselves.

When they came back home after the war it caught on with everyone. Cool how certain actions we take and things we do were influenced by history. Thank you for looking my friends and have a blessed day! : )